To study the effects of ibaraki virus on preimplantation mouse embryos collected from prepubertal ICR and BALB/cByJ mice (30-40 days old) by superovulation, zona pellucida-intact (ZPI) or free (ZPF) embryos (n=774) of 4- to 8-cell and morulae were exposed to 10** (5.8) TCID50 of the viurs up to 96 hours. The embryos were examined morphologically by observing the degeneration and hatching rates, and virologically and immunologically by determining the presence of infection with the virus, in addition, the effect of washing the embryos to remove virus possibly attached to was also investigated. The ZPI 4- to 8-cell embryos and morulae exposed to the virus showed considerably higher degeneration rate than those not exposed, for 96, and for 72 to 96 hours, respectively (p0.01). The ZPF 4- to 8-cell embryos and morulae exposed to the virus showed considerably higher degeneration rates than those not exposed, throughout the whole culture hours in vitro (p0.01). The ZPI 4- to 8-cell embryos and morulae not exposed to the virus showed considerably higher rates of hatched blastocyst than those exposed (p0.01). The virus infection rates of the ZPF 4- to 8-cell embryos and morulae were significantly higher than those of the ZPI embryos according to cell culture system. The viral antigen was detected exclusively on the zona pellucida of ZPF embryos by the immunofluorescent assay. In the ZPI embryos exposed to ibaraki virus, the virus was detected in the two times-washing groups, but not in the ten times-washing groups. The results indicated that zona pellucida of murine embryos would provide an effective protection and that ten times-washing of the ZPI embryos previously exposed to the virus was effective to remove virus from the embryos

In order to observe the pathological changes of kidney in rabbits infected with the viral haemorrhagic disease, the kidney tissues from the 91 rabbits infected with the viral haemorrhagic disease were examined by light and electron microscopy. On light microscopic observation, the kidney lesions were identified as haemorrhagic glomerular necrosis (33.0 %), membranous glomerulonephritis (20.9 %), thrombotic glomerulopathy (19.8 %) membranoproliferative glomerulonephritis (8.8 %), mesangial proliferative glomerulonephritis (8.8 %) ischemic acute tubular necrosis (7.7 %), and acute serous glomerulitis (6.6 %). On electron microscopic observation, cytoplasmic degeneration of mesangial cells, and irregular thickening of basement membranes with electron dense granular materials were observed. In podocytes swelling of mitochondria, dilatation of endoplasmic reticulum and extensive fusion of foot processes were also observed. Nonenveloped round icosahedral picornaviral particles with a diameter of 28-33nm were detected in the cytoplasm of degenerative endothelial cells, polymorphonuclear leucocytes, and monocytes

The frequency of appearance of HI antibody against Japanese encephalitis virus was investigated over the three-year period 1982 through 1984. The sample population consisted of 1306 cattle in Saitama prefecture (located in central Japan), and 536 cattle in Kagoshima prefecture (located in southern Japan). During the study period, there was no significant difference in the average antibody-positive rate between cattle in Kagoshima (68.8 %) and those in Saitama (65.5 %). Variations in the monthly antibody-positive rate and mean monthly antibody titer in the Saitama cattle followed a mountain-like pattern with the peak observed during summer. In the Kagoshima cattle, both parameters also increased in summer and these increases persisted even in winter. The distribution of antibody-positive rate as a function of age ranged from 64.0 % to 82.8 % in Saitama, though no correlation was observed between these two factors. In the Kagoshima cattle, however, the antibody-positive rate increased with age as follows; the values averaged 29.4 % in the one-year-old cattle group, 50.0 % in the two-year-old group, 47.4 % in the three-year-old group and 74.5 % in the four-year-old group. There was no significant correlation between the mean antibody titer and age in either Saitama cattle (15.3-22.5) or Kagoshima cattle (20.0-32.3)

A survey on the prevalence of internal parasites in the laboratory rats in the Chonnam and Kyonggi areas was carried out. A total of 208 rats was selected for necropsy and the parasites were collected from the organs and the fecal samples. The infection rate of the internal parasites was high as 63.9 % and eight species of parasites were identified. Among the species identified A tetraptera (21.6 %) and H diminuta (20.7 %) appeared with relatively higher infection rates than any other species identified. A significant difference in numbers of parasites was recognized between the regions as 8 species in Chonnam and 4 species in Kyonggi. The laboratory rats reared in stainless steel cage showed the higher infection rate than those in polycarbonate cage, with some exception in H spumosa and H nana. In this survey T crassicauda was firstly in the laboratory rats in Korea

Five hundred and forty-eight samples of pig heart muscle were collected from the abattoirs of many regions in Korea to reveal the frequency of Sarcocystis infections and to identify the species from June 1988 to April 1989. Heart muscle of the pigs was inspected for sarcocysts by the direct detection technique and for bradyzoites by the trypsin digestion technique. For examination of development of the parasites in the final host, 5 cross bred mature dogs, 5 puppies and 5 kittens were fed 100g, 50g and 50g of the infected meat respectively, four times in 2 days. Of 402 fattened and 146 older culled breeding pigs, 3 fattened pigs and 39 culled pigs were positive for Sarcocystis. Sarcocystis cysts from heart muscle measured an average of 425 x 169 micro m and bradyzoites an average of 15.6 x 3.5 micro m. Of 15 animals, only 2 puppies were infected with Sarcocystis. The prepatent period was 11 to 12 days and patent period was not examined since the puppies were infected with some another infections and one died on day 11 and another died on day 12 after ingestion of the meat. The sporulated oocysts were detected 11 days after ingestion of the meat and sporocysts 12 days from the puppy feces. The sporulated oocysts measured an average of 16.5 x 11.5 micro m and sporocysts an average of 12.6 x 7.9 micro m. On scaping examination of the intestinal mucosa, fully sporulated oocysts were detected in the tip of the intestinal villi. Considering above all descriptions, Sarcocystis in pig heart muscle in Korea was identified with Sarcocystis suicanis